C++依赖倒置原则

class Ireader
{
public:
	virtual string Getcontents() = 0;
};
class Book : public Ireader
{
public:
	virtual string Getcontents()
	{
		return "读本书!";
	}
};
class NewsPaper : public Ireader
{
public:
	virtual string Getcontents()
	{
		return "读报纸!";
	}
};
class EBook : public Ireader
{
public:
	virtual string Getcontents()
	{
		return "读电子书!";
	}
};
class Mother
{
public:
	void tellStory(Ireader* pi)
	{
		cout << pi->Getcontents() << endl;
	}
};
void TestDIP()
{
	Mother m;
	Book b;
	NewsPaper n;
	EBook eb;
	m.tellStory(&b);
	m.tellStory(&n);
	m.tellStory(&eb);

}